feat: add 2026 World Cup data (Spain champions)

Scrape all 104 matches, 48 squads, stadiums, and group data from English
Wikipedia. Spain beat Argentina 1-0 a.e.t. in the final; England third,
France fourth. Add 2026 to YEARS in seed.ts and scrape-wikipedia.ts.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

data/2026/worldcup.stadiums.json

@@ -0,0 +1,68 @@
+{
+  "stadiums": [
+    {
+      "name": "SoFi Stadium",
+      "city": "Inglewood"
+    },
+    {
+      "name": "NRG Stadium",
+      "city": "Houston"
+    },
+    {
+      "name": "Gillette Stadium",
+      "city": "Foxborough"
+    },
+    {
+      "name": "Estadio BBVA",
+      "city": "Guadalupe"
+    },
+    {
+      "name": "AT&T Stadium",
+      "city": "Arlington"
+    },
+    {
+      "name": "MetLife Stadium",
+      "city": "East Rutherford"
+    },
+    {
+      "name": "Estadio Azteca",
+      "city": "Mexico City"
+    },
+    {
+      "name": "Mercedes-Benz Stadium",
+      "city": "Atlanta"
+    },
+    {
+      "name": "Lumen Field",
+      "city": "Seattle"
+    },
+    {
+      "name": "Levi's Stadium",
+      "city": "Santa Clara"
+    },
+    {
+      "name": "BMO Field",
+      "city": "Toronto"
+    },
+    {
+      "name": "BC Place",
+      "city": "Vancouver"
+    },
+    {
+      "name": "Hard Rock Stadium",
+      "city": "Miami Gardens"
+    },
+    {
+      "name": "Arrowhead Stadium",
+      "city": "Kansas City"
+    },
+    {
+      "name": "Lincoln Financial Field",
+      "city": "Philadelphia"
+    },
+    {
+      "name": "Estadio Akron",
+      "city": "Zapopan"
+    }
+  ]
+}